Java:如何使用方法正确返回结果

Question

我编写了一个程序，通过调用方法来打印“基于可能的温度”季节 A、B、C 或 D。

代码:

import java.util.Scanner;
import javax.swing.*;

public class Seasons {

  public static void main(String[] args) {
    int inputTemp;
    String response = JOptionPane.showInputDialog(null,
            "Enter the temperature");
    inputTemp = Integer.parseInt(response);
    String message = "Based on the temperature of " + inputTemp
            + " it is most likely " + determineSeason(inputTemp);
    JOptionPane.showMessageDialog(null, message);

  }

  public static String determineSeason(int inputTemp) {
    String season = null;
    if (inputTemp > 130 || inputTemp < -20) { 
        JOptionPane.showMessageDialog(null,"Invalid");
    }

    else if (inputTemp >= 90) {
        JOptionPane.showMessageDialog(null,"summer"); }

    else if (inputTemp >= 70 && inputTemp < 90) {
        JOptionPane.showMessageDialog(null,"spring"); }
    else { 
        JOptionPane.showMessageDialog(null,"winter"); }

    return season; 
  }
}

该程序从我的方法中返回 JOptionPane 季节，然后从主方法中显示 JOptionPane，我需要它说“根据温度，季节是季节 A、B、C 或 D。

任何关于我所缺少的内容的建议将不胜感激!

Answer 1

defineSeason 应该是一个不处理 UI 部分的私有(private)方法(不与 Swing 组件交互)。

private String determineSeason(int inputTemp) {
    if (inputTemp > 130 || inputTemp < -20) { 
        throw new IllegalArgumentException("Invalid");
    }

    if (inputTemp >= 90) {
        return "summer";
    } else if (inputTemp >= 70 && inputTemp < 90) {
        return "spring";
    } else { 
        return "winter";
    }
}

season 不能是“Invalid”，您不会显示“it is most likely Invalid”，所以它是最好从方法中抛出异常，在调用方捕获它并显示错误消息窗口:

class Seasons {

    public static void main(String[] args) {
        String response = JOptionPane.showInputDialog(null, "Enter the temperature");
        int inputTemp = Integer.parseInt(response);
        try {
            String message = String.format("Based on the temperature of %d, it is most likely %s", inputTemp, determineSeason(inputTemp));
            JOptionPane.showMessageDialog(null, message);
        } catch (IllegalTemperatureValueException | NumberFormatException e) {
            JOptionPane.showMessageDialog(null, e.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
        }

    }

    private static String determineSeason(int inputTemp) throws IllegalTemperatureValueException {
        if (inputTemp > 130 || inputTemp < -20) {
            throw new IllegalTemperatureValueException("incorrect temperature value");
        }

        return inputTemp >= 90 ? "summer" : (inputTemp >= 70 ? "spring" : "winter");
    }
}

class IllegalTemperatureValueException extends Exception {
    public IllegalTemperatureValueException(String message) {
        super(message);
    }
}